Cobalt chemistry with mixed aminotroponiminate salicylaldiminate ligands: Synthesis, characterization, and nitric oxide reactivity

A new class of mixed aminotroponimine salicylalclimine ligands and their corresponding cobalt(II) complexes are reported. This work expands the family of cobalt(II) aminotroponiminato complexes to include salicylaldiminate and derivatized fluorescein moieties. The H(2)(iPr)SATI-n (n = 3, 4) ligands 3 and 4, respectively, contain an aminotroponimine moiety and a salicylalclimine fragment connected with an alkyl linker. In the H(2)(iPr)FATI-n (n = 3, 4) ligands 5 and 6, a derivatized fluorescein replaces the salicylaldimine fragment. The cobalt(II) complexes [Co((iPr)SATI-3)] (7) and [Co-2(iPrSATI-4)(2)] (9) were prepared and structurally characterized. The reaction of NO with both complexes ultimately results in the formation of a dinitrogen-containing species. The mononitrosyl, [Co((iPr)SATI-3)(NO)] (8), was isolated and characterized. The reactivity of [Co((iPr)FATI-3)] (10) and [Co((iPr)FATI-4)] (11) with NO mimics that observed for the salicylalclimine derivatives, as monitored by solution IR spectroscopy. When followed by fluorescence spectroscopy, reaction of 11 with NO evoked a 3-fold increase in emission intensity after 22 h.